Analysis of vital statistics, demographic and other population data often leads to important clues linking environmental exposures to specific diseases. The overall objective of this project is to identify and/or confirm the presence of various potential health hazards in the general environment through the mechanism of demographic investigations. The influence of environmental and occupational factors on mortality from chronic renal failure continues to be explored using mortality data for U.S. counties, census data, and data from the NIOSH occupational hazards survey. Data from the Health and Nutrition Examination Survey are being used to develop a new estimate of the number of persons who have been exposed to asbestos and to relate x-ray abnormalities to other measures of lung function. Data from a large British study of sudden infant death are being exploited to develop a measure of sinus arrhythmia in newborns. Existing data, including vital statistics, are also being used to make estimates of the clinical significance of findings from other epidemiologic studies.